Fuel Trims, MAF, VCDS, Data-logging, CSE Mathematics + Reading GRAPHS!

[r8wut]

I understand the temptation to blame the new o2 sensors for causing the multiple misfires across Bank 1 - I immediately did.

But the o2 lambda sensors have heating elements in them to get them up to temp very quickly in order to get the car running from open-loop to closed-loop operation.
Driving the RS for around 20-30mins post installation (probably too long), if there was any fault / failure of the o2 lambda heating circuits or similar a "related-DTC" would have definitely been set / flagged in either ECU in that timeframe - something along the lines of:

Oxygen (Lambda) Sensor : Heating Circuit: Short to Ground
Oxygen (Lambda) Sensor Heating; Open Circuit
Oxygen (Lambda) Sensor : Signal too Low
Oxygen (Lambda) Sensor Heating Circuit Malfunction
Oxygen (Lambda) Sensor; Internal Resistance too High


Whilst I appreciate the up-stream / pre-cat Lambda sensors which are identical by the way - are used by the ECU to regulate the Fuel Supply, the down-stream / post-cat Lambda sensors are used to monitor the efficiency of the CATALYTIC convertor.. and yes as correctly pointed out, can be mapped out / blanked out by a Tuner.

But, drawing inspiration from my CSE-level in Mathematical statistical probability and taking into account the Issues I outlined above - I would hedge a bet the HPFP(s) are at fault (being 17yrs old vs brand new o2 lambda sensors)

I also heard HPFP's can fail quicker or soon after a Major Service, including a Carbon Clean - because of the increased Air-flow and for the subsequent requirement by the ECU's for the HPFP's to work harder..

I guess we'll find out soon enough.. after which, if all is well - then yes I'll be taking the RS for a remap..
update to follow

[r8wut]

oh I agree it's been a quite a journey with this car (bleeding the clutch comes immediately to mind ) - but I'm a tenacious-petrolhead-sob

(as long as there's a good supply of decent Weissbier to cope with my frequent mood swings)

[r8wut]

ok - so the HPFP parts have arrived:

[r8wut]

Parts Ordered:

2x OE Hitachi HPFPs
2x OE Cam Follower / Tappets
6x Hex Bolts
2x Seal plugs / bolts
2x Washer rings

The part numbers are listed in the diagram below, for your benefit:

[r8wut]

Currently, my work-stack is such that I won't get around to installing and testing the above for a little while..

But I'm fairly confident when I do, install of the above will address the Issues experienced:

-Multiple Misfires
-Hesitation / jerky whilst accelerating from stand-still
-Sometimes stalling when coming to idle
-Slight Fuel Smell in Engine Bay
-Slight Fuel Smell in Oil Filler Cap
-Sooty Exhaust

hopefully I'll catch a break over the festive hols.. - if I'm not too hammered

[r8wut]

Ensure the oxygen sensors are plugged into the correct connector for each bank/ecu and not switched over/mixed up

If same

Swap front o2 sensors left n right

Could be faulty o2 sensor miss reading causing missfire on one bank

getting around to updating this thread.. well

Give the man a cigar Yes. in my haste the front Bosch o2 sensors (which are identical) got mixed up and plugged into the wrong bank, too much Weissbier Lesson learned.

Wish it as as simple as that.

But.

That's not where the story ends.

Indeed. It was only part of the reason why the RS was running like

[r8wut]

So, after switching over the lambda connectors.. and few runs etc the RS was running much better , albeit still wasn't running quite right..

Next up, proceeded with HPFPs + cam followers installation:

[r8wut]

Running much better.. but again not quite right..

ok so, I'm kinda skipping over some weeks & months of frustrating on/off diagnostic testing which really gave me a bit of a ball ache.. and I don't want you bore you

in the end I spoke with Doug @ MRC Tuning, regarding all I'd done and sending him some of my data analysis etc etc.

Obviously. the end goal here was a MRC Stage 2 Tune - but no point, if the RS really wasn't running quite right to begin with..

Doug is technically unrivalled in Audi experience - he said bring it down and we'll see what's what

[r8wut]

Took the RS down to MRC.

No mucking about - straight onto the Rolling Road.

Few minutes later - Doug comes over "Your RS4 has been mapped previously" what??

".. and it's pulling timing at the top end!"

I honestly thought it was stock Audi map on there.. although, admittedly I did have some suspicions..

anyway.. we discussed, agreeing someone somewhere at some point had put on a "crap map".

We agreed to flash back the RS4 ECU's back to the latest Audi stock map and .. take it from there..

[r8wut]

Doug Flashed Stock Audi RS4 maps onto the ECU's ..

another run ..

Baseline Stock Map:

Max Clutch Power : 377 PS
Max Clutch Torque : 391 Nm

[r8wut]

hhmm. Was rather disappointed with that, albeit stock - at least it now wasn't pulling timing at WOT!

BUT.

That was the least of my disappointment. During the run, I was outside and noticed, to my utter amazement, loads of bits of was flying out of the exhaust tips!

I showed Doug the mess on the floor outside after the run and he straight away (rather casually) said "your CATs have disintegrated!"

I was like, what? they're literally brand new Zinram 200 cells sports cats, highly recommended on the forums etc, German made!

He swiftly replied "I think you'll find the CATs are likely from China, not Germany!"

[r8wut]

Can't even make this up.

Some unknown <beep> ECU tune and the kicker, Zinram Sports CATs that had been clogged up / falling apart, causing issues, literally soon after installation.

After picking up the pieces of my disintegrated CAT (don't laugh) I had a chat with Doug.

No point proceeding with the MRC Stage 2 Tune, with these <beep>, (not made in Germany) falling apart downpipes..

I had to bite the bullet and went with Milltek downpipes Sports CATs , which MRC carry in stock.

The Milltek Sports CATs cost a fair bit more, but at least would bolt straight onto the existing Milltek CAT-back valved & Non-Resonated Cat-Back Exhaust System without drama.

There has been some speculation on Milltek quality, but Doug reassured me since these have gone back into production the quality has definitely improved, they have a warranty .. and to be honest, cannot be much worse than falling apart soon after installation!

Here's the pictures of the Zinram Sports CATs once they had been removed that had been clogged up / falling apart, causing some of the issues (you will see one downpipe is fine, whilst the other disintegrated):

[r8wut]

Anyway, more on that later.

Doug and the team proceeded to fit the Milltek Sports CATs.. and transfer over the Bosch o2 lambda's etc.

FINALLY.

The RS4 B7 went back on the dyno / rolling road for the MRC Stage 2 Tune


(was hoping for slightly better than the disappointing Baseline Stock Map of 377 PS)

[r8wut]